In the field of micromachining typified by the production of integrated circuit devices, design rules for finer pattern lithography have rapidly made progress to achieve highly integrated circuits and cost reduction. Along with this progress, the development of a lithography process that stably performs finer processing has been pursued strongly.
In response to such movement, a variety of chemically amplified resists comprising a radiation-sensitive acid generator that generates an acid upon exposure to radiation have been proposed, which are improved in sensitivity as resists by the catalysis of the acid. For example, Patent Document 1 discloses a combination of a resin having a t-butyl or t-butoxycarbonyl protecting group with a radiation-sensitive acid generator. Patent Document 2 discloses a combination of a resin having a silyl protecting group with a radiation-sensitive acid generator. In addition, many reports on chemically amplified resists have been made, such as a resist comprising: a resin having an acetal or ketal protecting group; and a radiation-sensitive acid generator (see e.g., Patent Document 3).
Patent Document 1: Japanese Laid-Open Patent Publication No. 59-45439
Patent Document 2: Japanese Laid-Open Patent Publication No. 60-52845
Patent Document 3: Japanese Laid-Open Patent Publication No. 2-25850
However, along with progress in design rules for a finer pattern lithography process, problems have been coming to the surface in terms of fluctuations in line width attributed to standing waves, deterioration in pattern profile attributed to standing waves, nano edge roughness or LEF (line end foreshortening; a phenomenon in which the film thickness of a pattern of lines gets thinner toward the edge of the pattern), and so on. Specifically, when a pattern having such problems is transferred to a substrate by treatment such as etching, the line width precision of the pattern may be reduced, leading to significant reduction in the electrical characteristics or the like of an integrated circuit device (see e.g., Non-Patent Documents 1, 2, 3, and 4). Therefore, the above-described performances, in addition to resolution performance required for conventional chemically amplified resists, are very important for responding to finer integrated circuit devices.
Non-Patent Document 1: J. Photopolym. Sci. Tech. (1998) p 571
Non-Patent Document 2: Proc. SPIE Vol. 3333, p 313
Non-Patent Document 3: Proc. SPIE Vol. 3333, p 634
Non-Patent Document 4: J. Vac. Sci. Technol. B16 (1), (1998) p 69